title: Submaximal ADP-stimulated respiration is impaired in ZDF rats and recovered by resveratrol.
abstract: Mitochondrial dysfunction and reactive oxygen species (ROS) have been implicated in the aetiology of skeletal muscle insulin resistance, although there is considerable controversy regarding these concepts. Mitochondrial function has been traditionally assessed in the presence of saturating ADP, but ATP turnover and the resultant ADP is thought to limit respiration in vivo. Therefore, we investigated the potential link between submaximal ADP-stimulated respiration rates, ROS generation and skeletal muscle insulin sensitivity in a model of type 2 diabetes mellitus, the ZDF rat. Utilizing permeabilized muscle fibres we observed that submaximal ADP-stimulated respiration rates (250-2000 μm ADP) were lower in ZDF rats than in lean controls, which coincided with decreased adenine nucleotide translocase 2 (ANT2) protein content. This decrease in submaximal ADP-stimulated respiration occurred in the absence of a decrease in electron transport chain function. Treating ZDF rats with resveratrol improved skeletal muscle insulin resistance and this was associated with elevated submaximal ADP-stimulated respiration rates as well as an increase in ANT2 protein content. These results coincided with a greater ability of ADP to attenuate mitochondrial ROS emission and an improvement in cellular redox balance. Together, these data suggest that mitochondrial dysfunction is present in skeletal muscle insulin resistance when assessed at submaximal ADP concentrations and that ADP dynamics may influence skeletal muscle insulin sensitivity through alterations in the propensity for mitochondrial ROS emission.
authors.affiliation: G. P. Holloway: Human Health and Nutritional Sciences, University of Guelph, 491 Gordon St., Guelph, ON, Canada, N1G 2W1. ghollowa@uoguelph.ca.
authors.forename: Brennan K
authors.initials: BK
authors.lastname: Smith
authors.forename: Christopher G R
authors.initials: CG
authors.lastname: Perry
authors.forename: Eric A F
authors.initials: EA
authors.lastname: Herbst
authors.forename: Ian R
authors.initials: IR
authors.lastname: Ritchie
authors.forename: Marie-Soleil
authors.initials: MS
authors.lastname: Beaudoin
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Smith
authors.forename: P Darrell
authors.initials: PD
authors.lastname: Neufer
authors.forename: David C
authors.initials: DC
authors.lastname: Wright
authors.forename: Graham P
authors.initials: GP
authors.lastname: Holloway
mesh_terms: D033742:Adenine Nucleotide Translocator 2 / Q000378:metabolism; D000244:Adenosine Diphosphate / Q000502:physiology*; D000818:Animals; D019069:Cell Respiration / Q000187:drug effects / Q000502:physiology; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism; D019803:Glutathione Disulfide / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D018482:Muscle, Skeletal / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D011924:Rats, Zucker; D000077185:Resveratrol; D013267:Stilbenes / Q000494:pharmacology
chemical_list: D033742:Adenine Nucleotide Translocator 2; D013267:Stilbenes; D000244:Adenosine Diphosphate; D006861:Hydrogen Peroxide; D005978:Glutathione; D000077185:Resveratrol; D019803:Glutathione Disulfide